gplugin/gplugin

Add a doc alias target and bump the meson requirement to 0.52.0

Testing Done:
Ran locally

Reviewed at https://reviews.imfreedom.org/r/582/
REVIEWBOARD_URL = "https://reviews.imfreedom.org/"
REPOSITORY = "gplugin/gplugin"
REPOSITORY_TYPE = "mercurial"
BRANCH = "default"
LAND_DEST_BRANCH = "default"
LAND_PUSH = False